The present invention relates to glazing systems and more particularly relates to glazing systems composed of a silicone spacer rod constructed from heat vulcanizable silicone rubber compositions which in the cured state has a Durometer A Hardness of at least 30 and a room temperature vulcanizable silicone sealant.
It has been a relatively recent architectural design of high rise buildings to have large window panes for most if not all of the exterior wall of the building. In general the tendency has been to increase the size of the window pane so as to cover as large an area of the exterior wall of the building as is possible. This design results both in an improved aesthetic effect in the appearance of the building, as well as providing a large amount of natural lighting to the interior of the building.
In the past, it was common to support such large glass window panes in such buildings by inserting them in metal support brackets, such that there was an exterior edge or bracket on the window frame which supported and held in place the window pane.
Recently, it has become highly desirable in terms of economy in the construction of such buildings, as well as improving the aesthetic appearance of the building, to have the window panes inserted flush with the exterior wall of the building such that there are no unsightly metal brackets or protrusions from the walls of the building. The means that has been provided for accomplishing this construction is to provide a window frame with a lip side extending perpendicular to the wall of the building and extending from the interior of the building flush to the exterior wall of the building. To this lip side there is appended perpendicular to it at the interior side of the building a resting side of the window frame on which the glass window pane can be rested. The glass pane is then held in place by applying a sealant around the interior faces of the glass pane or the edges of the pane or both, bonding the glass pane to the metal window frame. Thus, when the sealant is cured such a sealant completely supports and retains the window pane in place on the side of the building. This allows for a construction where the window pane is flush and in plane with the exterior wall of the building.
However, one major difficulty was encountered with such a construction in that the use of a silicone sealant as a sole supporting element of the window pane to the window frame of the building resulted in an undue load being placed on the sealant in some cases. Thus, in such a construction, the sealant had to withstand the total stresses of the window pane expanding and contracting, as well as the result of pressure differentials between the interior and the exterior of the building which might result in movement of the window pane.
Accordingly, to overcome this problem it was in some cases suggested that a spacer rod be inserted in the window frame around the edges of the window frame such that the window pane would rest upon and against the spacer rod. Then the sealant would be applied to join the edges of the glass pane with the window frame. The use of such spacer rods was for the purpose of acting as a cushioning device and as a stress sharer with the sealant in maintaining and supporting the glass pane in the window frame. Such spacer rods in the past have been fabricated of butyl rubber, vinylchloride, and Neoprene.
While Neoprene rubber has a desirable characteristic as a resting material because of its excellent hardness such that it can have a Durometer A of 75-90 or more, it does not have sufficient cushioning properties as a spacer rod along all the edges of the window pane.
Further in the case of the butyl rubber spacer rods, it was found such butyl rubber spacer rods in many cases did not have a sufficiently high Durometer A Hardness unless reinforcing material was incorporated in such rods and in general were very difficult to apply because of their unvulcanized state as they were used by the construction workers in the field.
In addition, in the case of Neoprene when utilized as a spacer rod it was found that such Neoprene had to be heated at very cold temperatures in order for it to be worked on properly and placed into the proper location in the window frame.
In addition, both butyl rubber tape and Neoprene would bleed out various uncured ingredients in their compositions which would gradually contaminate and degrade any sealant that came into contact with it.
In addition, if it was desired to join or make any other adhesions with such prior art spacer rods and other materials such joining and adhesion of other materials to such spacer rods was particularly difficult in some cases requiring vulcanization at the point of installation.
Accordingly, it was highly desirable to provide for an all-silicone spacer rod silicone sealant system for the installation of window panes that would be flush with the exterior side of buildings.
Accordingly, it is one object of the present invention to provide for a silicone glazing system composed of a spacer rod which is constructed from cured heat vulcanizable silicone rubber compositions having a Durometer A Hardness in the cured state of at least 30 and a room temperature vulcanizable silicone sealant.
It is another object of the present invention to provide a silicone spacer rod and a silicone sealant that are compatible with each other where the spacer rod will not degrade or effect the silicone sealant.
It is an additional object of the present invention to provide a spacer rod and a silicone sealant that are easy to apply in normal as well as abnormal construction temperatures and which, especially in the case of the spacer rod, can be handled with ease and facility in its installation in the window frame.
It is yet an additional object of the present invention to provide a process for the installation of window panes flush with the exterior wall of the building where said window panes are supported by silicone spacer rods and a silicone sealant.